1. Field of the Invention
The present invention relates to a communication control apparatus for a telecommunications system, and more particularly to a communication control apparatus applicable to a telecommunications system, such as a sensor network, a local area network (LAN), which is formed by a plurality of network node devices spatially distributed or carried on mobile bodies to transmit data therebetween, for obviating a collision between transmitted data ascribable to interference of electromagnetic waves or similar cause.
2. Description of the Prior Art
For allowing a plurality of spatially distributed nodes to transmit and receive data therebetween without any collision, available are a time division multiple access (TDMA) system and a carrier sense multiple access (CSMA) system such as a CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) system and a CSMA/CD (Carrier Sense Multiple Access with Collision Detection) system, as taught in Y. Matsushita et al., “Wireless LAN Architecture”, pp. 47, 53-59 and 69, Kyoritsu Shuppan Co., Ltd., Tokyo, Japan, 1996.
One of the problems with the TDMA system is that, when a central or management node expected to allot time slots fails, the entire telecommunications system goes down. In light of this, there have been proposed various methods of obviating a collision between transmitted data by causing the individual nodes to mutually adjust the allotment of time slots in a distributed coordination or self-organizing fashion without resorting to a central control server. For such mutual adjustment, each node transmits and receives periodic impulse signals to and from its neighboring nodes to interact with them.
More specifically, each node is adapted for using expressions modeling nonlinear oscillation to take account of the timing at which another node transmits an impulse signal to thereby adjust its own timing for the transmission of an impulse signal. With this adjustment scheme, the individual nodes execute mutual adjustment such that the transmission timing of an impulse signal from the own node is apart as far from the transmission timing of an impulse signal from another node as possible, implementing the allotment of time slots in a distributed coordination or autonomous fashion.
Further, when nodes are spatially distributed in a planer lattice or matrix arrangement, there may be implemented an optimum time-division transmission pattern in which only neighboring nodes, lying in a first range, mutually share a time slot, as also proposed in the past. More specifically, the transmission timings of nodes, lying in a third range and held in a particular positional relation free from collisions, are synchronized to each other, so that neighboring nodes, lying in the first range, can mutually share a single period with each other. Consequently, a time slot which each node is acquirable can be maximized. In this sense, the optimum time-division transmission and hence ideal, high-level communication efficiency is achievable.
However, the above-stated communication control system, implementing the optimum time-division communication by the individual nodes, is applicable to a telecommunications system or network in which a plurality of nodes are spatially distributed in a lattice configuration, but not to other types of telecommunications systems or networks not using the lattice configuration.